Perpetual calendar



FIG. 1 is a perspective view, showing my new design.

FIG. 2 is a rear view thereof.

FIG. 3 is a left end view.

FIG. 4 is a bottom plan view.

FIG. 5 is an inside face view in open condition.

The broken lines are shown for illustrative purposes only. 

The ornamental design for a perpetual calendar, substantially as shown and described. 